Thrombosis is one of the major problems of modern man and research directed to its control is a major health goal. The proposed program is designed to establish an interdisciplinary Thrombosis Research Center at Cornell University Medical College. The activity would represent the combined interrelated efforts of six major laboratories all working on the fundamental biochemical and physiological background of the human thrombotic process. An underlying theme which serves as a common denominator of the individual projects is the recognition of the unique and crucial role of the platelet and vascular components in thrombosis. The major scientific approaches to these problems will include (1) biochemical and ultrastructural analysis of the human platelet membrane, (2) characterization of the platelet as an inflammatory cell, (3) culture of human endothelial cells and study of endothelial cell myosin activity and, (4) surface activation and localization of interacting plasma enzyme systems.